Landing an aircraft is a very complex task. An experienced pilot calls upon conditioned responses to rapidly changing occurrences which are observed through sight, feel, hearing and kinesthesis. There are many control options available to the pilot, each affecting two or three variables. For example, if the pilot senses that he is too high and applies forward pressure on the control wheel, the aircraft will lower its nose, speed up, and move further down the runway and may be too fast to accomplish the stall desired for a good landing. The pilot must respond with coordinated use of several of the controls available to him. To accomplish a good landing, the pilot normally stabilizes as many of the variables as he can and then deals with the remaining ones with coordinated use of the controls.
Learning this complex operation is difficult for a student pilot, often requiring many hours of training. One of the main problems is learning how to observe the rapidly changing environment while maintaining control of the aircraft. For example, when an aircraft is landed, it must be "stalled" just as the wheels touch the ground. The pilot must accurately judge this altitude by looking out of the window while keeping the aircraft straight with the runway. He can not be looking at his instrument panel, and if he fixes his attention on one point, he will contact the ground at the wrong time and bounce the aircraft. Many experienced pilots often lapse into inattentiveness and make a poor landing.
Instrument pilots face the same problems in another environment. They fly an instrument landing system to an elevation of 100 to 200 feet, at which point the pilot must see the runway. He must then react to what he sees to correctly land the aircraft. Seaplane pilots often make bad landings due to their inability to judge height above smooth water.